The present invention relates to a hinge for a waterproof electronic device holding case and, more particularly, to a hinge capable of improving the waterproofing ability of a waterproof seal placed between the open end of an electronic device holding case and a lid.
A waterproof outdoor electronic device holding case proposed in JP 2002-134948 A or JP 10-308586 A has a case body and a lid connected to the case body by hinges. The lid is turned (pivots) on the hinge pins of the hinges for opening and closing. An electronic device holding case proposed in JP 10-117072 A or JP 2002-176272 A has a case body, a lid and a waterproof seal placed between the open end of the case body and the lid so as to be compressed between the case body and the lid. In this electronic device holding case, a lid fixing screw serves as a shaft for fastening a hinge to the lid, the lid fixing screw is connected to the hinge pin of the hinge, the lid is moved on one side by unfastening the screw to move the lid for opening and closing.
In those prior art electronic device holding cases, the lid turns on the hinge pin. When the lid is turned for closing on the hinge pin and the lid is almost completely closed, a compressive force compressing the seal acts in a direction at an angle α to a normal to the end surface of the case body on which the seal is placed as shown in FIG. 13. Consequently, a part of the seal nearer to the hinge cannot be compressed perpendicularly to the end surface of the case body, i.e., a contact surface of the case body with which the lid comes into close contact, and hence, in the seal, a possibility of not exercising an original waterproof function properly exists due to twisting or jamming. A waterproof seal proposed in JP 11-4084 A is provided with a plurality of protrusions capable of exercising a waterproof function when compressed even by a low force. Even an O-ring must be compressed perpendicularly to prevent the O ring from twisting and jamming.
The lid fixed with a hinge nut as mentioned in Patent document 3 or 4 is able to compress the seal properly. However, since the lid is fixed to the case body by the screw connected to the hinge and the movement (stroke) of the lid is dependent on the degree of screwing of the fixing screw as shown in FIG. 14, the lid does not necessarily follow a fixed path when the lid is opened or closed. For example, if the stroke of the lid is long, the axis of a fixing bolt 18 shown in FIG. 14 are liable to be tilted at an angle β to a normal to a contact surface between the lid and the case body. Consequently, the lid is dislocated in a lateral direction η and cannot be correctly positioned relative to the case body and hence close attention must be paid to avoid the twisting and jamming of the seal.
A hinge nut 19 must have a strength to withstand a squeezing force exerted thereon by the fixing bolt 18 and the resilience of the seal. Therefore, there are restrictive conditions for the size and material of the hinge nut 19 and hence it is difficult to form the hinge in a small size and small weight. The hinge nut needs machining work such as threading work.
Generally, fixation of a hinge to a case body needs troublesome work, such as screwing screws, press-fitting a hinge pin or staking a hinge pin after inserting the hinge pin in a bore, which increases man-hour.